Interchangeable adjustable resistance unit



April 3, 1952 v. J. CANZIANI ETAL 2,592,392

INTERCHANGEABLE ADJUSTABLE RESISTANCE UNIT Filed March 10, 1951 r0 '2' LL O I v =2 r $43 i i K! I? N N q 2 H N I HM; lllllllllllllllllllllfl 8 E N I "T I r I 83 mm r co 0 i N .D U a a 9 w m INVENTORS VICTOR J. CANZIANI DAVID C.SILVERMAN ATTORNEY ROBERT P. WIENER Patented Apr. 8, 1952 UNITED STATES PATENT OFFICE Victor J. Canziani and David C. Silverman, Brooklyn, and Robert P. Wiener, Bronx, N. Y., assignors to Fairchild Camera and Instrument Corporation, a corporation of Delaware Application March 10, 1951, Serial No. 214,932

This invention relates to interchangeable adjustable resistance units and, while it is of general application, it is particularly adapted to such units of the type adapted for assembly with other like units on a common continuous actuating shaft to form a multiple-unit adjustable resistance device.

Many electronic devices, such as electronic computers, require a large number of adjustable resistors and it is frequently required that a num ber of such devices be adjusted precisely in unison. When a number of such resistors are ganged together, the precision of adjustment of the resultant assembly is generally impaired by a certain amount of backlash in the coupling elements joining the individual shafts, or by lack of coaxiality in the shafts of the several resistors. Furthermore, in previous attempts to construct a single compact multiple-unit resistance device, the mechanical arrangement has been such that, if a particular resistance unit became defective in use, it has been difficult to replace the defective unit without removal and without complete disassembly of the whole device, At the same time, the resistance units utilized in such resistance devices are generally costly precision units and the several resistance units generally have different functional tapers, that is, resistance-displacement characteristics, so that, if a single unit fails, it is uneconomical to discard the entire device. It is also uneconomical to attempt to stock multiple-unit resistance devices having a large number of permutations in the functional tapers of the components of the resistance units.

It is an object of the present invention, therefore, to providea new and improved multipleunit adjustable resistance device which obviates one or more of the disadvantages of prior devices of this type.

It is another object of the invention to provide a new and improved multiple-unit adjustable resistance device which is characterized by one or more of the following advantages: a simple and compact construction; a precision which is not impaired by backlash or torsional deflection of the actuating shaft mechanism or lack of coaxiality in several shafts; ready interchangeability of the individual resistance units facilitating original assembly of a number of units of any desired individual functional tapers; and a construction in which the device, when assembled from a plurality of such interchangeable units, is effectively a rugged, rigid, unitary device.

In accordance with the invention, an interchangeable adjustable resistance unit adapted for 14 Claims. (Cl. 201-48) assembly with other like units on a common continuous actuating shaft to form a multiple-unit adjustable resistance device, comprises a cupshaped housing having an external peripheral clamping ridge at either end thereof and an annular resistance element disposed in said housing and provided with external connection terminals. The unit also includes an electrical wiper assem bly including a sleeve adapted for mounting on an actuating shaft and an electrical wiper mounted on said sleeve, said sleeve having complementary segmental extensions on opposite ends thereof for engaging similar sleeve extensions of like adjacent units, and means including a sliding contact and an external terminal for making electrical connection with the wiper.

Further in accordance with the invention, a multiple-unit adjustable resistance device includes a continuous actuating shaft, a plurality of interchangeable resistance units of the type described mounted thereon, a clamping ring engaging each pair of adjacent housing clamping ridges, and a pair of end plates including shaftsupporting bearings.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing, while its scope will be pointed out in the appended claims.

Referring now to the drawing, Fig. 1 is an exploded perspective view of an interchangeable resistance unit embodying the invention; Fig. 2 is a longitudinal elevation, partly in section along the line 22 of Fig. 3, of a multiple-unit adjust-1 able resistance device comprising three units of the type illustrated in Fig. 1; while Fig. 3 is an end elevation of the device of Fig. 2 with the back end plate or the adjacent unit of a multipleunit device removed.

Referring now more particularly to Figs. 1-3, inclusive, of the drawing, there is illustrated a multiple-unit adjustable resistance device comprising a common continuous actuating shaft I0 and a plurality of interchangeable adjustable resistance units adapted for assembly with other like units on the shaft I0. Each of the resistance units is of the type shown in Fig. 1 and comprises a cup-shaped housing I I having external periph eral clamping ridges I la, I lb at either end thereof. The opposed faces II c, I Id of the ridges I la, IIb, respectively, comprise tapered wedging surfaces for a purpose described hereinafter. The housing member II also has complementary peripheral surfaces He, II on opposite ends thereof for engaging similar housings of like adjacent units. Specifically, these peripheral end surfaces are in the form of complementary steps which interlock with complementary steps ofadjacent housing units. The housing II has a radially extending wall member I I g which serves primarily as a bearing element and positioning device for the electrical wiper assembly sleeve described hereinafter. It also serves as a closure for one end of the housing member and as a closure for the opposite end of an adjacent housing member.

Within the housing II is disposed an annular resistance element I2 which may be in the form of an elongated resistance strips disposed about the inner periphery of the housing II, but insulated therefrom by the insulation sleeve IS. The resistance element I2 is provided with external terminals I4, I4 secured to amounting block I5 of insulation material. It will be understood that the ends of resistance strip I2 are electrically connected with the terminals I4, I4 internally by connectors not shown.

The resistance unit also includes an electrical wiper assembly comprising a sleeve It for mounting on the shaft lil and an electrical wiper II mounted on the sleeve. Specifically, a cylindrical block of insulation material 'IB is rigidly secured to the sleeve I6, while a slip ring I9 is, in turn, mounted on the block I8 and supports and is electrically connected to-the wiper H. The block I8 is maintained in fixed axial position'and in any predetermined or adjusted angular position on the sleeve I6 by an end plate 26 which clamps a shoulder 16a of sleeve I6 against the end of the block 18.

"'Thesleeve I6 hascomplementary segmental extensions I60, I Gel on opposite ends thereof for engagingsimilar sleeve extensions of like adjacent units. Preferably each of these extensionsconsists of an approximately 180 segment and one of the extensionsfor example, the extension I6d includes a pair of slots I6e forming therebetween a resilient finger I61 adjacent one edge of the segment which is sprung to engage the extending segment of an adjacent sleeve and serves to eliminate backlash between adjacent sleeves. The wiper assembly described is contained wholly withinits associated housing-whilethe sleeve I6 hassubstantially the same mean axial lengthas the housing I I. By the term mean axial length is meant the length between corresponding axial end points, for example, the length of the sleeve l6 less one of the extensions. This construction ensures a close fitting assembly substantially eliminating end play between adjacent housings and wiper assemblies of the several resistance units included. in a device.

.The resistance unit also includes means for making a sliding contact between the wiper I1 and one of the external electrical connection terminals 2|, 2 I. This sliding contact may comprise a pair of opposed brushes 22,22 extending'from a clamping plate 23 and engaging diametrically opposite points of the slip ring I9. The elements 22, 22,23 are insulated from the resistance strip I2 by a;.strip of insulation material 2.6. The elements .23 and 24 andthe'terrninal block I5 are secured to each other in position'by any suitable means such as a machine screw 25.

In order to fasten together a plurality of interchangeable resistance units .such as shown in Fig. 1, there isprovided a clamping ring 26 engaging each pair of adjacent housing clamping ridges. Each of the clamping rings 25 is of channel-shaped cross section and somewhat narrower in width than the adjacent clamping ridges at their roots. Each of the clamping rings 26 is also of a diameter somewhat less than that of the clamping ridges and is provided with projecting device.

tabs 26a, 261) at either end thereof, one of the tabs, for example, the tab 26b, being tapped for engagement by alocking-screw 21.

The resistance device 'isprovided with a stiff but resilient driving connection between the shaft I 6 and one of the sleeves I 6, preferably the sleeve of the unit nearest the actuating member of the This driving connection may be in the form of a pin 28 fixedly extending through the shaft I10 so that one side of the pin extends approximately along a diameter of the shaft. This bearings 2 9a and 30a, respectively. The end plates 29 and 30 have a peripheral flange 29!) and recess 30b, respectively, complementary to and individually engaging corresponding adjacent peripheral recess lie and flange II J, respectively, of the associated housing II. The plates 29 and 30 are provided also with external peripheral clamping ridges 26c and 300, so that they may be clamped to their respective adjacent housings by clamping rings '26. One of the end plates, for example, the end plate 30, includes mean for restraining the shaft l0 against axial movement. This restraining means may take the-form of a pair of C washers 3|, '3| whichare sprung into peripheral grooves Illa, I (la on=eitherside of the bearing 30a. One of the-end plates, for examplethe end plate 30, includesprovisions for mounting the multiple-unit resistance'devicawhich means may be in the form of tapped holes 30d, 3012 which may be engaged by supporting screws mounted in any convenient supporting structure.

It is believed that the operation of the multiple-unit adjustable resistance device of the invention will be clear from the foregoing description, such operation being, in general, like that of conventionalelements of this type. Rotation of shaft I0 may be effected by any suitable manual or automatic actuating mechanism. Rotation of the shaft I0 is effective to rotate the series of interlocked sleeves I6 which support the slider assemblies including the wiper contacts I! which engage their respective resistance strips I2. Due to the resilient interlocking engagement between the several sleeves I6, there is no backlash and'no appreciable torsional deflection. Therefore, the wiper elements I! of the several resistance units are adjusted accurately in unison. At the same time, the common supporting shaft I0 forthe sleeves I6 maintains an accurate coaxial alignment between the wiper assemblies of the severalresistance units. At the same time, the interlocking surfaces He and Hf of adjacent housing members II maintains an accurate coaxial alignment between these housing .members and the resistance strips mounted therein and forms with the end plates 29 and'30 a dust-tight housing. By tightening the several clamping rings 26 on the adjacent clamping ridges of the housing II and the end plates 29, 30, there results arigid .unitary over all construction. I

Thus it will be seen that with the construction described, there is provided a multiple-unit adjustable resistance device incorporating the several advantages discussed above. With this construction, resistance units of various functional tapers, for example, units having resistance-displacement characteristics following apower law, a trigonometric function, etc., may be stocked individually and thereafter assembled into devices of any desired number of units including any desired permutations of functions. Thereafter, if any of the resistance units should become defective or worn in use, it may be readily removed by loosening one or more of the clamping rings 26, replaced by a unit from stock, and Freadily reassembled. In addition, the phase relation between the functional tapers of the several units may be readily adjusted merely by loosening the clamping ringsholding the housing of a particular resistance unit and rotating that housing until the desired phase relation is obtained. This may be effected without in any way disturbing the phase relation of other resistance units of the assembly. The relative phase relation of the wipers I! of the several resistance units is initially adjusted at the time the assembly [1, l8, I9 is clamped in place by securing the clamping plate 20. This relative phase relation is retained even after replacement of a particular unit. On the other hand, the relative phase relation of any particular wiper assembly may be adjusted, not only by adjusting its housing, as described above, but also by loosening its individual clamping plate 20 and this will not disturb the relative phase relations of the several remaining wipers [1.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

-1. An interchangeable adjustable resistance unit adapted for assembly with other like units on a common continuous actuating shaft to form a multiple-unit adjustable resistance device comprising: a cup-shaped housing having an external peripheral clamping ridge at either end thereof; an annular resistance element disposed in said housing and provided with external connection terminals; and an electrical wiper assembly including a sleeve adapted for mounting on an actuating shaft an electrical wiper mounted on said sleeve, said sleeve having complementary segmental extensions on opposite,ends thereof for engaging similar sleeve extensions of like adjacent units; and means including a sliding contact and an external terminal for making electrical connection with said wiper.

2. An interchangeable adjustable resistance unit adapted for assembly with other like units on a common continuous actuating shaft to form a multiple-unit adjustable resistance device comprising: a cup-shaped housing having an external peripheral clamping ridge at either end thereof, said ridges having opposed tapered wedging surfaces; an annular resistance element disposed in said housing and provided with external connection terminals; and an electrical wiper assembly including a sleeve adapted for mounting on an actuating shaft and an electrical wiper mounted on said sleeve, said sleeve having complementary segmental extensions on opposite ends thereof for engaging similar sleeve extensions of like adjacent units; and means including a sliding contact for making electrical connection with said wiper.

3. An interchangeable adjustable resistance unit adapted for assembly with other like units on a common continuous actuating shaft to form a multiple-unit adjustable resistance device comprising: a cup-shaped housing having an external peripheral clamping ridge at either end thereof and having complementary peripheral flanges and recesses on opposite ends thereof for engaging similar housings of like adjacent units; an annular resistance element disposed in said housing and provided with external connection terminals; and an electrical wiper assembly including a sleeve adapted for mounting on an actuating shaft and an electrical wiper mounted on said sleeve, said sleeve having complementary segmental extensions on opposite ends thereof for engaging similar sleeve extensions of like adjacent units; and means including a sliding contact for making electrical connection with said wiper.

4. An interchangeable adjustable resistance unit adapted for assembly with other like units on a common continuous actuating shaft to form a multiple-unit adjustable resistance device comprising: a cup-shaped housing having an external peripheral clamping ridge at either end thereof; an elongated resistance strip disposed about the inner periphery of said housing and provided with external connection terminals; and an electrical wiper assembly including a sleeve adapted for mounting on an actuating shaft and an electrical wiper mounted on said sleeve, said sleeve having complementary segmental ex tensions on opposite ends thereof for engaging similar sleeve extensions of like adjacent units; and means including a sliding contact for making electrical connection with said wiper.

5. An interchangeable adjustable resistance unit adapted for assembly with other like units on a common continuous actuating shaft to form a multiple-unit adjustable resistance device comprising: a cup-shape housing having an external peripheral clamping ridge at either end thereof; an annular resistance element disposed in said housing and provided with external connection terminals; and an electrical Wiper assembly ineluding a sleeve adapted for mounting on an actuting shaft, a block of insulation material mounted on said sleeve, and a slip-ring and electrically connected wiper mounted on said block, said sleeve having complementary segmental extensions on opposite ends thereof for engaging similar sleeve extensions of like adjacent units; and means including a contact engaging said slip ring and an external terminal for making electrical connection with said wiper.

6. An interchangeable adjustable resistance unit adapted for assembly with other like units on a common continuous actuating shaft to form a multiple-unit adjustable resistance device comprising: a cup-shaped housing having an external peripheral clamping ridge at either end thereof; an annular resistance element disposed in said housing and provided With external connection terminals; and an electrical Wiper assembly including a sleeve adapted for mounting on an actuating shaft and an electrical wiper mounted on said sleeve, said sleeve having complementary segmental extensions on opposite ends thereof for engaging similar sleeveextensions of like :adjacent ;.units;:.said' wiper. assemblyzbeing "con- 1 ta-ined' wholly withinsaid housing and said. sleeve having: substantially the same meaniaxiallength as" said housing; and means: including a sliding contact and an external terminal for making electrical connection withv said wiper.

7. An interchangeable adjustable resistance unit adapted for assembly with other like units on'a common continuous actuating shaft to .form

a multiple-unit. adjustable resistance device comprising: a cup-shaped housing. having an :external peripheral clamping ridge at either end thereof; an annular resistance element disposed :insaid housing, and provided with external connection terminals; and an electrical wiper assembly including a sleeve'adapted for mounting on an actuating shaft and anielectrical wipermountedon said sleeve, said sleeve having approximately 180 segmental extensions on opposite ends thereof for engaging similar sleeve extensions of like adjacent'units; and means including a sliding contact-and an external terminal for making electrical connection with said wiper.

8. An interchangeable adjustable resistance unit adapted for assembly with other like units on a common continuous actuating shaft to form a multiple-unit adjustable resistance device comprising: a cup-shaped housing having an external peripheral clamping ridge at either end thereof; an annular resistance element disposed in said housing and provided with external con nection terminals; and an electrical wiper assembly including a sleeve adapted for mounting on an actuatingshaft and an electrical wiper mounted on said sleeve, said sleeve having complementary segmental extensions on opposite ends thereof for engaging similar sleeve extensions of like adjacent units, one of said segmental exten- 'sions including-a resilient finger adjacent one edge thereof to eliminate backlash between adjacent sleeves; and means including a sliding contact and an externalterminal for making electrical connection with said wiper.

said shaft and an electrical wiper mounted on said sleeve, said sleeve having complementary segmental extensions on opposite .ends thereof I for engaging similar sleeve extensions of like adjacent units, and means including a sliding contact and an external terminal for making electrical connection With said Wiper, a clamping ring engaging each pair of adjacent housing clamping ridges; and a :pair of end plates including shaft-supporting bearings.

10. A multiple-unit adjustable resistance device comprising: a continuous actuating shaft, a plurality of interchangeable resistance units, each including a cup-shaped housing having an external peripheral clamping ridgeat either end thereof, an annular resistance element disposed in said housing and provided with external connection terminals, and an electrical wiper assembly including a sleeve adapted for mounting on said shaft and an electrical wiper mountedon said sleeve, said :sleeve having complementary segmental extensions on oppositexends thereof for engaging .similar sleeve extensions of like clamping ridges; and a pair of end plates inshaft-supporting bearings.

segmental :extensionsnon opposite ends adjacent "units; and'qmeans including a". sliding contact: and'tan external terminal for making electrical.connectionwithsaid wiper, a clamping ring engaging'each pair of adjacent housing clampingridges; a resilient driving connection between saidshaft andonly a terminal one'of said'sleeves; and a pair of end plates including 11'. A multiple-unit adjustable resistancef device comprising: a continuous actuating shaft, a

plurality of interchangeable resistance ,runita' sembly including a sleeve adapted for mounting" on said shaft and an electrical wiper mounted on said sleeve, said sleeve having complementary segmental extensions on opposite ends thereof for engagingsimilar sleeve extensions of like adjacent units, and means including a sliding contact and an external terminal for making electrical connection'with said wiper, a clamping ringengaging each pair of adjacenthousing eluding shaft-supporting bearings, one of said end plates including means for restraining said shaft against axial movement.

12. A multiple-unit adjustable resistance device comprising: a continuous actuating shaft, a plurality of interchangeable resistance units,

.each including a cup-shaped housing having an external peripheral clamping ridge at either end thereof, an annular resistance element disposed in saidvhousing and provided with external "connection terminals, and an electrical wiper assembly including asleeve adapted for mounting on said shaft and an electrical wiper mounted on said sleeve, said sleeve having complementary thereof for engagingsimilar sleeve extensions of like adjacent units, and means including a sliding contact and an external terminal for making electrical connection withsaid wiper, a clamping ring engaging each pair of adjacent housing clamping ridges; and a pair of end plates including shaft-supporting bearings, one of said end plates including provisions formounting the device.

. 13'. A: multiple-unit adjustable resistance device comprising: acontinuous actuating shaft,

nection terminals, and an electrical wiper assembly including a sleeve'adapted for mounting on said shaft and an electrical wiper mounted 'onsaid sleeve,zsaid sleeve having complementary segmental extensions on opposite ends thereof for engaging: similar sleeve extensions of like adjacent units, and means including a sliding contact. and an'external terminal for making electrical connection with said wiper, a clamping :ring engaging each pair of adjacent housing clamping ridges, the end member of each housingxserving as a closure for the adjacent housing; and a pair of end plates including shaftsupporting. bearings.

14. A multiple-unit adjustable resistance device comprising: a continuous actuating shaft,

a .IPIUIEElltY' ofinterchangeable resistance units,

each including-a2 cups-shaped: housing having an 9 external peripheral clamping ridge at either end thereof and having a peripheral flange and a complementary peripheral flange on opposite ends thereof for engaging similar housings of like adjacent units, and annular resistance element disposed in said housing and provided with external connection terminals, and an electrical wip'er assembly including a sleeve adapted for mounting on said shaft and an electrical wiper mounted on said sleeve, said sleeve having complementary segmental extensions on opposite endsithereof for engaging similar sleeve extensionsi of like adjacent units, and means including a sliding contact and an external terminal for making electrical connection with said wiper; a clamping ring engaging each pair of adjacent housing clamping ridges; and a pair of end plates including shaft-supporting bearings and having a peripheral flange and a peripheral recess complementary to and individually engaging corresponding adjacent peripheral flange and recess of said housings.

VICTOR J. CAN ZIANI.

DAVID C. SILVERMAN. ROBERT P. WIE-NER.

No references cited. 

